Structure of the Immature Dengue Virus at Low pH Primes Proteolytic Maturation

Abstract

Intracellular cleavage of immature flaviviruses is a critical step in assembly that generates the membrane fusion potential of the E glycoprotein. With cryo-electron microscopy we show that the immature dengue particles undergo a reversible conformational change at low pH that renders them accessible to furin cleavage. At a pH of 6.0, the E proteins are arranged in a herringbone pattern with the pr peptides docked onto the fusion loops, a configuration similar to that of the mature virion. After cleavage, the dissociation of pr is pH-dependent, suggesting that in the acidic environment of the trans-Golgi network pr is retained on the virion to prevent membrane fusion. These results suggest a mechanism by which flaviviruses are processed and stabilized in the host cell secretory pathway.

Viroporins: structure, function and potential as antiviral targets

“…Similar peptides also induce mitochondrial membrane permeability, although the relevance of this to natural infection is unclear (Catteau et al, 2003). Single-TMD topology has also been predicted for M, implying that two membrane-associated forms may exist, potentially as a result of the tight turn (3 aa) between the two TMDs found within particles (Kuhn et al, 2002;Yu et al, 2008;Zhang et al, 2003). Much like Vpu and 6K, investigators are yet to assign a functional role to potential M-mediated channel activity, although mutation of a highly conserved His39 in the first TMD reduced dengue virus spread without affecting polyprotein processing or the formation of prM-E heterodimers, yet this did prevent glycoprotein secretion, which may conceivably relate to channel-forming activity (Pryor et al, 2004).…”

“…The 75 aa small M (membrane) protein is cleaved from the viral E protein by signal peptidase as a prM precursor, which is then processed in the Golgi and acidifying secretory compartments by furinlike proteases into M and the pr peptide (Junjhon et al, 2008;Keelapang et al, 2004;Kuhn et al, 2002;Wong et al, 2012;Yu et al, 2008). The release of virions from the cell surface results in the loss of pr and resultant formation of a mature, infectious virion (Junjhon et al, 2008(Junjhon et al, , 2010Yu et al, 2008Yu et al, , 2009.…”

“…The release of virions from the cell surface results in the loss of pr and resultant formation of a mature, infectious virion (Junjhon et al, 2008(Junjhon et al, , 2010Yu et al, 2008Yu et al, , 2009. prM is required for efficient trafficking of E to the cell surface and accelerated cleavage of prM is detrimental to virion production (Junjhon et al, 2008(Junjhon et al, , 2010Keelapang et al, 2004).…”

Dissociation of HSV gL from gH by αvβ6- or αvβ8-integrin promotes gH activation and virus entry

“…Different viruses deal with this problem with different strategies. The closest example is probably that of alpha and flaviviruses; cognate proteins enable the transport of the E1 (or E) fusion proteins; however, the cognate proteins are cleaved in the trans-Golgi network and, in contrast to gL, do not remain in heterodimeric association with their partners (41,42).…”

Неугодная Иммунология

“…Геном DENV имеет протяженность 11 кб. Вирусная РНК трансли-руется в отдельный сложный белок (polyprotein), ко-торый рассекается в цитоплазме клетки клеточными и вирус ными протеазами на три структурных белка: капсидный (capsid, C); премембранный (premembrane, prM); оболочечный (envelope, E proteins); и на 7 нес-труктурных белков (NS1, NS2A, NS2B, NS3, NS4A, NS4B и NS5) [135].…”